In recent years, various electronic payment and electronic transaction functions using a mobile phone with an electronic wallet function has become more and more popular. A common application is where the mobile phone serves as a contactless smart card from which value of an electronic wallet is added or deducted provided that the mobile phone is placed within a radio sensing range of a reader supporting the electronic wallet function, e.g., the radio sensing range is within a radius of around 10 centimeters. FIG. 1 is a block diagram of a mobile phone 10 having the foregoing electronic wallet function in the prior art. The mobile phone 10 communicates with an external near-field communication (NFC) reader 16 via the NFC technique. The mobile phone 10 comprises a subscriber identity module (SIM) card 11, a security chip 12, an NFC chip 13, an antenna 14, and a control circuit 15. When the mobile phone 10 is within a sensing range of the NFC reader 16, the NFC chip 13 writes via the antenna 14 information (e.g., value-added/value-deducted information) from the NFC reader 16 to the security chip 12, or responds data (e.g., available balance) stored in the security chip 12 to the NFC reader 16.
However, following problems may occur when the mobile phone 10 is applied to perform the electronic wallet function. A first problem may occur when a user replaces a mobile phone, the data (e.g., available balance) originally stored in the security chip 12 cannot be accessed and transmitted to a new mobile phone. A second problem may occur, since the NFC chip 13 is only powered by a battery (not shown) of the mobile pone 10, the battery needs to have remaining power when the mobile phone 10 performs electronic payment. Therefore, a situation may occur where after a user enters a railway station, he cannot leave the railway station since the battery becomes empty due to frequent utilization of the mobile phone 10 (e.g., answering a phone call). The foregoing problems may incur significant inconveniences of the user.
To solve the foregoing problems, a Single Wire Protocol (SWP) for accessing an SIM card by a mobile phone via the NFC technique is developed. As shown in FIG. 2, a mobile phone 20 comprises an SIM card 21 conforming to the SWP, an NFC chip 23 conforming to the SWP, an antenna 24, and a control circuit 25. When a battery of the mobile phone 20 becomes empty, the NFC chip 23 can generate power supply by electromagnetic waves transmitted from an NFC reader to maintain operation. Data originally stored in a security chip is stored into the SIM card 21 and is applied to different mobile phones. However, since most electronic wallet function providers, e.g., bank systems, public transport system, and the like, independently operates, the electronic wallet functions cannot be integrated to a single SIM card released by a telecommunication company thereby creating limitations of the service range of an electronic wallet function supported by the SIM card 21.